Tens of thousands of people marched in Mexico City on Saturday to protest President Enrique Peña Nieto's proposed constitutional amendment to establish marriage equality nationwide.

Mexico's Supreme Court has recognized same-sex couples have a constitutional right to marry in a series of rulings beginning in 2012. But because the Supreme Court doesn't have the power to simply overturn all state marriage laws at once, couples in most states still must sue in order to marry.

Marco Ugarte / AP

Marriage equality has already spread to 10 states, as well as Mexico City, without becoming an issue in national politics. But when the president proposed amending the constitution so that it would be legal across the country, a coalition of conservative groups mobilized in opposition.

The president's proposal was declared "frozen" by congressional leaders of his own party, though two other left-wing parties are still hoping to get marriage equality legislation on the agenda.

But there are two proposals to outlaw marriage equality also potentially pending in Congress. These were proposed as two separate "citizens initiatives," and groups collected the hundreds of thousands of signatures required to force Congress to consider them.

Marco Ugarte / AP

Saturday's march follows 132 local marches held in cities around the country on Sept. 10, which organizers say had a total of 1.2 million participants.

Organizers said this protest in Guadalajara had 270,000 people, but the city’s civil protection authority reportedly estimated attendance between 45,000 and 50,000.

The Sept. 24 march was sponsored by the National Front for the Family — a coalition of mostly Catholic-led family service organizations and anti-abortion groups — and the evangelical National Christian Union for the Family.

"This shows that society is willing to do what it takes to defend family," said Juan Dabdoub, whose group ConFamilia, is part of the National Front for the Family and launched the first initiative to outlaw marriage equality. "The next step is the elections. If they vote against the initiative, we will vote against them."

"It's clear that the majority of Mexico is in favor of family," said Deputy Cecilia Romero of the opposition Partido de Acción Nacional, in an interview with BuzzFeed News following the march.

Romero is one of the most vocal members of Congress in opposition to the president's proposal and hoping to reverse the Supreme Court's rulings.

"Legislators represent the people, and we need to hear the voice of the people," she said.

Saturday's march suggested those opposed to marriage equality not only command a substantial organizing capacity, but also financial resources. The march had six Jumbotrons along the route broadcasting live footage of the event, and marchers carried thousands of pre-printed flags with the National Front for the Family logo.

And this rendition of the classic, "La Cucaracha."

"To this protest we have come for family for marriage and the right to educate," sang the performers.

The owner of this sign was asked by an organizer to lower it, because "they're saying on social media that this is a religious march."

J. Lester Feder/BuzzFeed News

LGBT groups have fought back against the conservative mobilization with allegations that the church is breaking laws against religion being involved in politics. (Mexico has a history of strictly limiting churches, including banning priests from voting for many years.)

The group Equality Mexico has filed legal complaints against several Catholic archdioceses for encouraging participation in the marches.

A group called the National Pride Front retaliated on Thursday by naming several church leaders they say are gay, in a move that was roundly criticized by other LGBT activists.

Hugo Valdemar, spokesman for the Archdiocese of Mexico City, alleged that Mexico's non-discrimination watchdogs have been "co-opted" by the LGBT movement after a Mexico City official protested a publication in the church newsletter as "hate speech," and said Mexico was "at the beginning of a gay dictatorship."

Mexico's movement has drawn international support, including from Brian Brown, head of the US group National Organization for Marriage, as well as an international federation called the World Congress of Families.

Mario Romo, director of Red Familia — one of the lead groups in the National Family Front — confirmed to BuzzFeed News that foreign activists were in Mexico City this weekend to discuss forming a Latin American “front for the family.” He also said that Ludovine de la Rochere of the French anti-marriage-equality group La Manif Pour Tous was in town this weekend.

The Colombian outlet Semana reported earlier this month that Mexico’s evangelical party, Encuentro Social, had bought a flight to Mexico City for a Colombian lawmaker active in recent protests against Colombia’s education minister, who is a lesbian. (Hernandez did respond to messages from BuzzFeed News.) The report also said activists were coming from Peru and Panama.

Also on Saturday, the National Pride Front organized a small counter protest on the other side of the circle where the National Front for the Family held its rally. Police reportedly said the event drew 500 people.